AXILLARY NODE DISSECTION IN PATIENTS WITH BREAST-CANCER DIAGNOSED THROUGH THE ONTARIO BREAST SCREENING-PROGRAM - A NEED FOR MINIMALLY INVASIVE TECHNIQUES

OBJECTIVE: To determine the role of axillary node dissection by studyi ng patient and tumour characteristics of invasive breast cancer throug h the Ontario Breast Screening Program (OBSP). DESIGN: A retrospective evaluation. SETTING: The London, Ont., branch of the OBSP. PATIENTS: Three groups of women seen were studied: 50 women with screen-detected breast cancers, which were palpable and detected by the nurse-examine r, 62 women with occult screen-detected breast cancers and 353 age-mat ched women with invasive breast cancer from the LRCC prospective datab ase, who served as controls. MAIN OUTCOME MEASURE: The proportion of i nvolved axillary nodes within the 3 groups based on patient and tumour characteristics. RESULTS: Twenty-five (22.3%) of the 112 women had sc reen-detected tumours less than 1 cm in dimension, but only 1 had an i nvolved axillary node. Twelve (19%) of the 62 women with occult screen -detected tumour's had involved lymph nodes compared with 17 (34%) of the 50 women with palpable screen-detected cancers (NS). In the contro l group tumour dimension less than 1 cm versus 1 cm or larger had a ma rked effect on the probability of axillary node involvement (12.5% v. 40.7%, p = 0.001). In the palpable screen-detected group 3 times as ma ny women with outer quadrant or central lesions had involved nodes as those with inner quadrant lesions (38% v. 12%) and for those with a fa mily history of breast cancer almost twice as many had involved axilla ry nodes. In occult screen-detected patients there was more nodal invo lvement in patients aged 60 years or less than in those older than 60 years (35% v. 10%, p = 0.042); only 4 of 41 patients older than 60 pea rs had involved nodes at surgery. A significant difference in nodal in volvement was found with respect to high or intermediate grade versus low grade lesions in the occult group (44% v. 12%, p = 0.033). In the control group, tumour grade (intermediate and high [45.3%] v. low [20. 0%]) and hormone replacement therapy (HRT) (current or recent use [56. 5%] v. no use [34.5%]) were significant findings (p < 0.001 and p = 0. 005 respectively). CONCLUSIONS: Women older than 60 years with tumours smaller than 1 tm had a low probability of nodal positivity (0% to 8. 7%), but there is insufficient information in this group to give a 95% or better prediction of nodal status at the time of surgery. Studies of minimally invasive techniques such as sentinel node biopsy are need ed in this group to minimize surgical morbidity in these women who, as a result of early diagnosis, have an excellent long-term outlook.